The soil microbial biomass acts as a source and sinks of the plant nutrients. It is sensitive to the changes in the ecosystem stability. The aim of this study was to investigate the microbial biomass C and N content of topsoil (0-5 cm) under different land uses (forest and agricultural lands) located in the Agdaci Village, Bartin. Ten individual soil samples were taken from each site (forest and agricultural lands) in this region. This study also aimed to established relationship between microbial biomass C (C-mic)-N (N-mic) and other physico-chemical characteristics of soil. The average microbial biomass C was found as 1076.01 +/- 45.68 mu g g(-1), 522.01 +/- 45.68 mu g g(-1), respectively for the forest and agricultural soils. As with microbial biomass C, the average microbial biomass N was found as 118.71 +/- 10.68 mu g g(-1), 43.02 +/- 3.63 mu g g(-1), respectively for the forest and agricultural soils. Independent samples t test result showed a significant difference in microbial biomass C and N among the study areas. Microbial biomass C and N were shown to be significantly correlated to the soils physico-chemical properties, such as particle size distribution, organic C, total N, lime content and pH.